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Biological Chemistry

Protein Motion Capture

Studies extend utility of thioamide fluorescent probes of protein folding

by Carmen Drahl
April 9, 2012 | A version of this story appeared in Volume 90, Issue 15

Credit: J. Am. Chem. Soc.
Petersson’s team made this thioamide-labeled α-synuclein by ligating two peptides (red and blue).
Thioamide-labeled alpha-synuclein protein (a protein implicated in Parkinson’s disease), made by native chemical ligation of two peptides (red and blue).
Credit: J. Am. Chem. Soc.
Petersson’s team made this thioamide-labeled α-synuclein by ligating two peptides (red and blue).
Credit: Filmed and edited by Kirk Zamieroski for C&EN
Petersson explains the concept of protein motion capture with help from his hands and some sticky notes.

A pair of studies could pave the way for researchers to use thioamides, barely perceptible molecular probes, to track the protein-folding faux pas associated with diseases. E. James Petersson and his team at the University of Pennsylvania previously used thioamides, which differ from a protein’s amide by one oxygen-to-sulfur swap, as fluorescence-quenching probes. The probes adjust fluorescence intensity depending on a protein’s movements. They can be dropped unobtrusively into many locations on a protein, providing more detailed information than bulky probes that can fit only into one or two spots. Now, the researchers have discovered that thioamides work with fluorophores that don’t overlap with a protein’s intrinsic fluorescence (J. Am. Chem. Soc., DOI: 10.1021/ja3005094). His team also made thioamides compatible with a protein assembly method called native chemical ligation, which enabled the study of α-synuclein, a protein implicated in Parkinson’s disease (J. Am. Chem. Soc., DOI: 10.1021/ja2113245). Petersson says he’d like to improve the technique so it can easily insert thioamides in the middle of a protein; so far it works best for the ends.


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